The Relationship of BMI (Body Mass Index) and Sagittal Spinal Profile

PURPOSE: This study was done to determine the relationship of the sagittal spinal profile in normal subjects to the BMI.

METHODS: 101 normal medical students were recruited for the study, from which 73 had complete sets of data. The BMI was measured using a weighing scale and the height using a meter ruler. The sagittal spinal alignment was measured via non contact Video Raster Stereography (VRS) v 2.0 software and Formetric Instrument System. Data was analysed with ANOVA, simple linear regression and Pearson’s Correlation; with p< 0.05 set for significance

RESULTS: Of the 73 completed data, 56 were normal (BMI between 18.50 to 24.90 kg/m2); 4 overweight, and 13 underweight. None were obese. BMI and thoracic kyphosis had a positive correlation (p=0.031) with r=0.596; a rise of 1kg/ m2 causing an incremental 0.759 degree increase in kyphosis. BMI and lumbar lordosis had a positive correlation (p=0.002) with r=0.729; a rise of 1kg/m2 causing 0.9 degree increase in lordosis. BMI and sacral inclination had a positive correlation (p=0.02) with r=0.658; a rise of 1 kg/m2 causing 0.753 degree increase in sacral inclination.

CONCLUSION: An increase in BMI causes an increase in thoracic kyphosis, lumbar lordosis and sacral inclination.